Study: Pack straps cut blood flow and performance

Unless I'm using poles for skiing or hiking, I often get tingling in my finger tips while carrying a heavy pack. It turns out I'm not alone and the problem may be more than a minor nuisance, loss of fine motor control and increased fatigue may also be problems. Last month, a paper was presented at a meeting of the American Physiological Society that demonstrated how much even a moderate pack affects blood flow. 

Using ultrasound and a pulse oximeter, the scientists measured brachial artery pressure as well as capillary flow in the finger tips. After 10 minutes, only a 26 pound load was sufficient to reduce blood flow in the arm by about 43% and in the finger tips by about 54%. They blame this on the straps compressing the axillary vein. It's particularly noteworthy for mountaineers since this reduction could make us more prone to frostbite.

The study suggests that redesigning pack straps could improve blood flow. Unfortunately, the paper doesn't indicate which pack they tested on subjects but I'd guess it was a standard S-shape design. Nor does it mention whether a sternum strap was used, a common "feature" that tends to increase pressure on that axillary vein while impeding breathing efficiency. 

This study reminds me of the tumpline that Yvon Chouinard was selling in the early 1980's (for $5.50). Based on the design used by porters in Nepal, this simple strap put nearly all the weight on the head. Of course it never caught on because Westerners generally lack strong neck muscles. 

However, a study published in Nature in 1986 found that we were too quick dismiss this low-tech load carrying device. Normally there is a straight line increase in energy cost of carrying extra weight; e.g. add 20% of body weight, consume 20% more energy. The researchers found that this did not apply when the weight is carried on the head. Measurements of African tribe women walking on a treadmill showed that the could carry 20% of their weight without any increase in energy consumption versus unweighted. Beyond that, the increase was proportional with 30% of body weight increasing energy cost by 10% and 40% of body weight requiring 20% more energy. Yet another reason those Sherpas kick our butts at high altitude.

Study: Birth Control for Brain Injury

Even though I've long been a helmet advocate for many outdoor sports (biking, climbing, skiing, etc.), I've also been vocal about how inadequate most helmet really are. For starters, most of the ones commonly worn do not prevent concussion, contrary to popular belief. Of course helmets can only withstand a certain amount of force too, often far less than many people realize. So the bottom line is, helmets or not, traumatic brain injuries (TBIs) are still going to happen.

This new study shows that injections of progestrone, an ingredient in birth control pills, can significantly reduce the effects of TBI. The randomized, double-blind trial found that 6 months after patients experience severe trauma, those who received the progesterone shots for five days after the accident were in much better shape.

Having witnessed the results of a nasty TBI in more than one friend, I wish this research had been done years ago. But should any of you in the future have friends or family with a TBI, it would be well worth checking with their doctors about this protocol.

Study: Rock climb for aerobic fitness

When they hear the term "aerobic conditioning," most people think of things like running and cycling. Indeed, rock climbing probably doesn't occur to many as a way to improve heart and lung function. But researchers in Italy put climbing to the test and found that it's actually very aerobic according to a report just published in the Journal of Strength & Conditioning Research.

The scientists enlisted 13 recreational rock climbers (8 men and 5 women) and tested their aerobic fitness (VO2max, etc) in a lab. Then the subjects strapped on a portable system for measuring oxygen uptake and climbed easy routes on an 80-foot high wall. After the climb, blood lactate samples were taken.

What they discovered was that climbers of both genders naturally choose a speed that puts us near our performance/anaerobic threshold (I don't use the term lactate threshold because it's obsolete) and maintain this level of exertion. Of course, this makes sense because we generally want to get up a route quickly without going so hard that we flame out.

This level of exertion (about 73% of VO2max) is what the ACSM considers a good level for maintaining cardio fitness. Not surprisingly, they also found that rock climbers tend to have superior aerobic fitness (VO2 max around 40), roughly in the 85th percentile of the normal population.

As many of us know, climbing in an indoor gym is a form of moderate- to high-intensity interval training (something that gets a lot of buzz in the fitness world these days). The typical length of each bout, including recovery, is 9 minutes and this is repeated 10 to 15 times per session, with two to three sessions per week. In this study, they found that climbing burned 1000 - 1500 calories per week.

The bottom line is rock climbing is both good resistance training, which we already knew, and also decent aerobic training. Of course, if you have higher goals such as mountaineering, you still have to do endurance aerobic workouts and serious resistance training (read: lifting weights).

Study: Bear spray really works

Kind of reassuring for folks who travel in grizzly country. This study was just published in the Journal of Wildlife Management:

We present a comprehensive look at a sample of bear spray incidents that occurred in Alaska, USA, from 1985 to 2006. We analyzed 83 bear spray incidents involving brown bears (Ursus arctos; 61 cases, 74%), black bears (Ursus americanus; 20 cases, 24%), and polar bears (Ursus maritimus; 2 cases, 2%). Of the 72 cases where persons sprayed bears to defend themselves, 50 (69%) involved brown bears, 20 (28%) black bears, and 2 (3%) polar bears. Red pepper spray stopped bears' undesirable behavior 92% of the time when used on brown bears, 90% for black bears, and 100% for polar bears. Of all persons carrying sprays, 98% were uninjured by bears in close-range encounters. All bear-inflicted injuries (n = 3) associated with defensive spraying involved brown bears and were relatively minor (i.e., no hospitalization required). In 7% (5 of 71) of bear spray incidents, wind was reported to have interfered with spray accuracy, although it reached the bear in all cases. In 14% (10 of 71) of bear spray incidents, users reported the spray having had negative side effects upon themselves, ranging from minor irritation (11%, 8 of 71) to near incapacitation (3%, 2 of 71). Bear spray represents an effective alternative to lethal force and should be considered as an option for personal safety for those recreating and working in bear country.

Bottomline: you are safer using pepper spray than a gun if attacked by a bear. Not convinced? Read this report by one of the top bear researchers in Alaska. He strongly advocates pepper spray as the primary defense.

Study: Geezers on Everest

Now that the mad dash to the South side of Everest has begun, it looks to be a banner year for accidents and fatalities. With the North side closed because of the Chinese publicity stunt, the South Col route will be more crowded than ever.

What makes this the perfect storm for death is the new stipulation that nobody can go above Camp 2 until May 11. At only 21,500 feet, that is still a long ways from the top (29,028 feet). Then the sheep, er I mean climbers, will be corralled in base camp for 10 days from May 1st to the 10th so they lose even some of that acclimatization.

Assuming the fake Olympic flame actually reaches the summit on schedule for the evening news—a big IF—the climbers in Nepal then have 20 days to get to the top. By June 1st, the Khumbu icefall (photo) is so dangerous only those with a death wish will still be going through. So there will be lots of poorly acclimatized wealthy clients popping Diamox like candy and quietly shooting up dexamethasone all ready to rush up in the small window of opportunity.

As if that combination wasn't bad enough, a study published last Fall in the journal Biology Letters makes the prognosis even grimmer for those over 60. Entitled "Effects of age and gender on success and death of mountaineers on Mount Everest," it presents a statistical analysis for 15 years (1990 - 2005) of people making their first attempt.

The results indicate that your odds of summitting diminish past the age of 40, which kinda sucks. From about age 25 to 40, the odds of reaching the top are about 1 in 3. After that, it's a linear drop off to about a 1 in 8 chance of success at age 60.

But the odds of dying also go up past the age of 60, which really sucks. Until that age, the odds of your becoming a corpse are about 1.5%. The newbie sexagenarians face a 5% chance of kicking the bucket while on the mountain (Everest veterans have better odds). If the geezers do make it to the top, there's roughly a 25% chance they won't make it home alive!

This research is brought to us by the same scientist, Raymond Huey (who really knows his fruit flies and lizards), that showed using oxygen on Everest and K2 greatly increases the chance of survival and that Everest was only climbable less than one third of the past 570 million years due to low oxygen levels on the planet.

New Frostbite Procedure

File this one under: Good to know, hope I never need it.

I've never had frostbite though I've certainly had plenty of cases of "screaming meanies" (ask any ice climber if you don't know what that is). But as a mountaineer, frostbite is something that I need to be prepared for--quite a few of my friends have lost bits of fingers and toes.

This week, a paper was presented at the annual meeting of the Society of Interventional Radiology about a breakthrough treatment for frostbite that has the potential to prevent amputations. The technique involves using an IV to infuse the affected limb with a drug (Tenectaplase) through arteries upstream of the injured area so this likely isn't something that will be done in the field. The results appear to be a dramatic improvement over the standard protocols, which often resulted in small blood clots that wreak havoc on thawing tissue.

Since this research is so new, if you end up in the hospital with frostbite, it's likely that you may have to inform your doctor about the procedure. The press release gives a nice summary of the research. Here is the PowerPoint presentation if you want full details and the typical gory photos.

Study: Climbing hurts

Half of the climbers in gyms and at crags have been injured bad enough in the past year that they had to take at least one day off. One third have chronic overuse injuries such as elbow and shoulder tendonitis. Over a quarter suffer an acute injury, such as a torn A2 pulley in a middle or ring finger, from pulling harder than their body could handle. Yet only 10% of the waylaying injuries came from a fall.

That's the result of a survey of over two hundred climbers in Britain that was published last December in the British Journal of Sports Medicine. Titled "The epidemiology of rock climbing injuries," the authors also found that climbers are a stubborn lot when it comes to seeking medical attention. Only 11% went to a doctor and 18% to a physical therapist for treatment while 14% asked the advice of other climbers.

While half of all climbers bashing themselves up isn't a good thing, at least we aren't as bad as dancers at abusing our bodies. Another survey in Britain found that 80% of professional dancers had suffered an injury in the previous 12 months.

The study of dancers also found that 25% have had eating problems (anorexia and/or bulemia) and 10% were underweight to the point that it threatened their health. This question wasn't tackled in the climber survey but it's quite likely that eating disorders are nearly as common in the sport climbing and bouldering communities.

This study reinforces the danger of overdoing it in any sport. Overuse injuries are the ones most likely to take you out of action. But they are also the most easily prevented by getting sufficient rest, training underdeveloped muscles, and eating properly.

Study: Climber's High No Myth

No doubt you have heard of the "runner's high," which is the buzz achieved by an endurance workout. It has long been speculated that this blissful feeling results from the release of endorphin, a natural opiate produced by the body, but it had never been proven and some scientists considered this a myth.

Recently, scientists in Germany demonstrated that two hours of running does indeed cause the brain to release endorphins. In addition, the opiates preferentially bind to the prefrontal and limbic areas of the brain, which are involved with emotional processing and the suppression of pain.

As reported in the journal Cerebral Cortex, ten runners worked out for two hours and then underwent a PET scan. This is similar to a CT scan that digitally dissects the body except a radioactive isotope is injected into the bloodstream and the PET detects where it is metabolically active. In the case of the runners, the scan showed that opiate receptors in the brain after exercise were occupied by far greater amounts of endorphin. This also corresponded to an increase of euphoria and happiness at the end of the runs; the more intense the feelings, the more endorphin was binding to receptors.

While this study was conducted on runners, it also applies to all athletes and you don't have to work for two hours to experience it. Runners, cyclists, and other endurance athletes can fairly easily get into the "zone" after a half hour of working out.

It's fair to say that most climbers feel a strong buzz when they get to the top of a long, strenuous pitch. We may get a similar feeling on easier terrain only after a lot of vertical gain. In the case of crack climbing, that endorphin blast helps us ignore the pain in our feet. Climbers are frequently accused of being adrenalin junkies but we may really just be addicted to endorphin.

Study: Exercise and moderate drinking can be healthy

After a fun day of climbing, skiing, biking, or whatever, one of life's great pleasures is to relax with a good beer in hand. And there can be no denying that a great dinner is enhanced by a fine wine.

Yet practically every book on sports nutrition admonishes athletes against drinking alcohol, labeling it as empty calories. The mass media tells us booze is good one day and evil the next, pitching one doctor against another to stir the pot without taking a good look at the research. It is certainly confusing but new research is showing that moderate drinking plus exercise is indeed healthier than exercise without drinking or drinking without exercise.

Last month, a study was published in the European Heart Journal that looked at 20-years of data for nearly 12,000 people in Denmark. They found that those with the lowest risk of heart disease and the lowest risk of death from any cause were those who both worked out and drank a bit of alcohol (1 to 14 drinks per week). The people with the highest risks of an early demise were the non-drinkers who never exercise.

Of course, in Denmark they drink real beer instead of the mass-produced swill that is heavily consumed in the US. If you choose to imbibe, selecting a microbrew with lots of hops will give you the highest dose of antioxidants, vitamins, and flavonoids. Similarly, rich red wines are higher in the good stuff than whites.

On the other hand, drinking to excess is one of the surest ways to get fat and lose muscle. The extra calories don't help and the alcohol is converted in the liver to acetate which reduces fat burning. Heavy alcohol consumption also reduces testosterone and raises cortisol levels which lead to muscle wasting.

Study: Tired muscles

In my previous post on lactic acid, I mentioned that it is no longer considered a factor in muscle fatigue. One of the leading theories holds that it is the hydrogen ion released during the conversion of lactic acid to lactate that causes fatigue. As the hydrogen ions accumulate, the pH of the muscle cells drops (from about 7.1 to 6.4) and the thinking held that this causes the fatigue. Other suggested causes of tiredness have been the accumulation of phosphate and the loss of potassium.

Now there is a new study published in Proceedings of the National Academy of Sciences that indicates muscle fatigue is caused by calcium leaking into the cells. It's pretty heavy reading but the New York Times has a good article that explains the findings in lay terms.

It is the release of calcium in a muscle cell that actually makes it contract. When the calcium is reabsorbed, the muscle relaxes. But it's an imperfect process and some of the calcium leaks out, which keeps the muscle from contracting at full force. Worse, that calcium also helps an enzyme eat away at the muscle fibers.

The interesting part of all this is that it may lead to new ways for athletes to fight off fatigue. They've already developed a drug that plugs the calcium leaks and allows mice to exercise 20% longer. But we're still many years from having a magic pill that will give us the same benefit. And no, eating more calcium isn't the answer either.

Study: Higher Genes

Many people who have suffered at high altitude while watching their climbing partner charge on up a slope have blamed their own fitness. Although it is certainly advantageous to raise your performance threshold (the term lactate threshold is based on an outdated understanding of how the body works) and your VO2max, there may be something else to blame: your parents.

On his Medicine for the Outdoors blog, Paul Auerbach discusses a new paper published in High Altitude Medicine & Biology. Last year, a scientific expedition that climbed Mt. Everest conducted a battery of tests on the team. One of their findings was that a specific gene (ACE I-allele) is associated with better performance at extreme altitude. This backs up a previous study on Mt. Blanc that first showed the possible connection.

Of course, whether you have the gene insertion or not, it is still wise to reach the mountains in the best shape possible. For mountaineering, that also means more body fat (insulation and energy stores) than low-altitude athletes consider desirable.

Another study in the same journal showed that there may indeed be a connection between HAPE and HACE (high altitude pulmonary and cerebral edema), which have long been considered separate maladies. At least to this layman, it always seemed likely that both of these potentially fatal altitude problems were related. Now we have indirect measurements that show edema in the lungs also comes with raised intercranial pressure.

Study: The High Price of Health

It's actually cheaper to be fat and out of shape than to be healthy.

Of course, you've probably noticed this at the grocery store when comparing mass-market products created by mega-corporations to foods in the natural food section. Certainly the cost of eating healthy makes an impact when walking out of Whole Foods (aka Whole Paycheck) carrying a $100 of groceries in a single bag.

Exercise ain't cheap either, even for an outdoor athlete. Depending on your sports of choice, the cost of gear can be substantial. And more than likely you'll be logging a lot of car and plane miles to get to prime destinations for play. Even working out indoors at a gym can be pricey, either for a membership or the cost of equipment to train at home.

Okay, enough with the obvious. There is now scientific evidence that it's less expensive to be unhealthy. Using data from the Netherlands (2003), researchers created a mathematical model to predict lifetime health costs of lean non-smokers, obese non-smokers, and lean smokers. It turns out that the "healthy-living" group has the highest cost on society. Why? Because we live longer. And that means more expensive health interventions in the long run. On the bright side, our health costs are the lowest until around age 56.

There is even more new proof that healthier people longer. In a study just published in Circulation, over 15,000 men around age 60 were evaluated for cardio fitness on a treadmill and then tracked for all causes of death. They found that the healthiest people reduced their risk of death by 50% compared to moderately health and 70% compared to the least fit. The health benefit was linear too--the fitter you become, the better your odds of living longer.

So live healthy and live long...but be prepared to pay for it.

Protein Power?

Last week, the LA Times offered up a taste test of four different protein bars. The article also talks briefly about why and when you might want to consume these things, though it doesn't mention alternatives. The Clif Builder's bar came out on top but it's a dubious distinction when the panel found that they all taste artificial, this one just slightly less so.

Clif bills the Builder's as the "only all natural protein bar" despite containing a lot of processed sugar ("evaporated cane juice" is marketing speak for table sugar), heavily processed soy (most likely from genetically modified plants), and unnecessary added vitamins and minerals (men should watch out for iron). Sure a Builder's Bar delivers more protein than normal candy bars but it's hardly natural.

By comparison, you can get the same amount of protein from eating three mozzarella sticks, a handful of nuts, half a can of tuna, or a few pieces of beef jerky. Real food. Not some amorphous blob designed by the marketing and chemistry departments. And there is no need to fear saturated fats; we'll look at that myth later.

As outdoor athletes, we need more protein than is normally recommended for desk jockies (0.36 g per pound of body weight). Particularly if you are trying to lose weight while building muscle, you should be consuming about double that (0.75 g to 1.0 g), which works out to 135 grams per day for a 180 lb. person. Besides building muscle and providing energy, a recent study showed that protein also helps curb the appetite better than fat or carbohydrate. So adding protein to your diet is a good thing. But you don't have to get it from a candy wrapper.